Bound states in the continuum in a chain of coupled Mie resonators with structural disorder: theory and experiment

We study the impact of structural disorder on a radiative lifetime of symmetry-protected bound state in the continuum (BIC) and a bright mode in a one-dimensional periodic chain of coupled Mie resonators. Through experimental, simulation, and theoretical approach, we reveal an unusual linear decay in the radiative quality factor of the BIC with the increase of the disorder amplitude, contrasting with the quadratic decay observed in recent studies. We also investigate modes with different symmetries and show that the behavior of the quality factor in a strongly disordered system depends on the mode’s multipolar origin. In addition, we found that in a disordered finite chain, the quality factor of Fabry–Pérot modes is governed by intraband interactions of modes. To study the behavior of localized states in disordered systems, we also analyze the emergence of Anderson localization. Our findings are pivotal for the practical application of BICs, particularly in natural and self-assembled photonic structures where structural disorder plays a crucial role.